EXCHANGE 


A  STUDY  OF  THE  SOLUBILITIES  OF  LIQUIDS 

IN    LIQUIDS.     THE  PARTITION  OF   THE 

LOWER  ALCOHOLS  BETWEEN  WATER 

AND     COTTONSEED     OIL. 


DISSERTATION. 

Submitted  to  the  Board  of  University  Studies  of  The 

Johns  Hopkins  University  in  conformity  with 

the  requirements  for  the  degree  of 

Doctor  of  Philosophy 


by 

BENJAMIN  BLACKISTON  WROTH 
1916. 


A  STUDY  OF  THE  SOLUBILITIES  OF  LIQUIDS 

IN    LIQUIDS.     THE  PARTITION  OF    THE 

LOWER  ALCOHOLS  BETWEEN  WATER 

AND     COTTONSEED     OIL. 


DISSERTATION. 

Submitted  to  the  Board  of  University  Studies  of  The 

Johns  Hopkins  University  in  conformity  with 

the   requirements   for  the   degree   of 

Doetor  of   Philosophy 


by 

BENJAMIN  BLACKISTON  WROTH 
1916. 


fO 


Gettysburg  Compiler  Print. 
Gettysburg,  Pa. 


TABLE  OF  CONTENTS. 

Acknowledgment 4 

Introduction    5 

Materials   8 

Procedure  9 

Results 11 

Tables 14 

Discussion  of  Eesults 17 

Summary 20 

Biography    21 


371462 


ACKNOWLEDGMENT. 

This  work  was  undertaken  at  the  suggestion  of  Asso- 
ciate Professor  Reid,  and  the  author  desires  to  take  this 
opportunity  of  expressing  his  sincere  thanks  to  him  for 
his  untiring  and  constant  interest. 

The  author  also  desires  to  express  his  gratitude  and 
sincere  thanks  to  Professor  Morse,  Professor  Remsen, 
Associate  Professor  Reid,  Associate  Professor  Lovelace, 
Associate  Professor  Frazier,  Professor  Ames,  former 
Associate  Professor  Acree  and  the  late  Professor  Jones 
for  valuable  instruction  and  assistance  received  during 
his  university  course. 


A  STUDY  OF  THE  SOLUBILITIES  OF  LIQUIDS 

IN    LIQUIDS.     THE  PARTITION  OF    THE 

LOWER  ALCOHOLS  BETWEEN  WATER 

AND     COTTONSEED     OIL. 


INTRODUCTION. 

According  to  the  commonly  accepted  partition  law  a 
solute  C  is  partitioned  between  two  immiscible  solvents, 
in  contact  with  each  other, 

_^_.  Sa 

cb  sb 

in  which  Ca  and  Cb  are  the  concentrations  of  C  in  the 
solvents  A  and  B,  respectively,  r  is  a  constant  ratio,  and 
Sa  and  Sb  are  the  solubilities  of  the  solute  in  the  two 
solvents.  It  has  frequently  been  shown  that  r  is  constant 
only  when  the  solute  C  exists  in  the  two  solvents  in  the 
same  molecular  aggregation.  The  equality  of  Ca/Cb  =  r 
=  Sa/Sb  has  been  proved  for  iodine  partitioned  between 
water  and  carbon  disulfide,  bromof  orm,  and  carbon  tetra- 
chloride  by  Jakowkin.1  His  results  are  as  follows: 

From  solubilities  in  From 

r  * ,          partition 

A.  B.  Sa  Sb  experiments. 

CS2  H2O  230        -5-    0.3387  =  679  685 

GHBrs  H2O  189.55    -*-    0.3387  =  559  558-5 

CCh  H2O  30.33    -s-    0.3387  =    89.6  89.7 

Of  course,  this  law  holds  strictly  only  in  the  ideal  case 
where  the  solvents  A  and  B  are  absolutely  immiscible  and 
neither  modifies  the  solvent  power  of  the  other  in  the 
slightest.     If  any  appreciable  amount  of  A  dissolves  in 
i    Z.  physik.  Chem.  18.  590  (1895). 

5 


V 


6 


B,  the  solvent  power  of  B  for  C  is  thereby  altered  and 
vice  versa.  Steiner2  and  Gordon3  have  shown  that  the 
solubilities  of  gases  in  water  are  much  altered  by  the 
presence  of  even  small  quantities  of  salts  in  solutions. 
However,  this  is  not  contradicting  the  partition  law,  but 
simply  saying  that  the  value  of  Sa  and  of  Sb  should  be  the 
solubilities  of  C  in  A  saturated  with  B  and  in  B  satu- 
rated with  A,  rather  than  the  solubilities  in  the  pure  sol- 
vents. 

Jakowkin4  has  also  shown  that  r  changes  progressively 
with  the  amount  of  solute  C  and  that  the  value  of  r  ap- 
proaches Sa/Sb  when  larger  and  larger  quantities  of  C  are 
added.  When  Ca  and  Cb  approach  zero,  r  approaches 
another  limit  which  is  more  properly  its  ideal  value,  as 
only  when  Ca  and  Cb  are  very  small  are  the  solvents  A  and 
B  unaltered  by  the  presence  of  C.  When  larger  amounts 
of  C  are  present  A  and  B  become  mutually  more  soluble 
and  the  properties  of  both  solvents  are  altered.  In  the 
present  work  the  smallest  practicable  amounts  of  C  were 
used. 

Assuming  Ca/Cb  =  r  =  Sa/Sb,  since  there  are  five  quan- 
tities in  this  double  equation,  we  may  determine  any  three 
and  calculate  the  other  two.  Thus  if  we  measure  Ca  and 
Cb  and  thus  find  r  we  need  to  measure  Sa  in  order  to  calcu- 
late Sb. 

Such  results  must,  of  course,  be  considered  in  the  light 
of  the  above  considerations  and  be  accepted  with  reserve. 
The  present  work  was  undertaken  with  the  aim  of  ap- 
plying this  to  the  calculations  of  solubilities  in  the  case  of 
certain  very  soluble  liquids.  The  results  are  considered 
as  suggestive  rather  than  as  conclusive.  They  mean 
something,  but  just  what  they  mean  may  be  left  for  fu- 
ture consideration. 

In  a  series  of  experiments  in  which  ethyl  alcohol  was 
partitioned  between  cotttonseed  oil  A,  and  water  B,  r  was 

2.    Wied.  Ann.,  52,  275  (1894) 

3  Z.  physik.  Chem..  18,  520  (1895). 

4  Ibid.,  18,  590  (1895). 


found  to  be  28.3.  The  average  of  a  series  of  experiments 
gave  the  solubility  of  alcohol  in  the  oil,  Sa  as  21.1  g.  per 
100  cc.  Calculation  gives  Sb  as  the  solubility  of  the  alco- 
hol in  100  cc.  water  as  600  g.  There  are  many  substances 
of  which  water  dissolves  several  times  its  own  weight. 
For  instance,  100  cc.  of  water  dissolve  339  g.  of  cadmium 
chlorate  at  0°  and  549  g.  at  65°.  In  these  cases,  however, 
though  the  solubility  is  great,  it  is  still  limited.  One  hun- 
dred grams  of  water  dissolve  907  g.  of  calcium  iodide  at 
0°  but  stops  there,  and  if  we  shake  it  with  910  g.,  3  g.  of 
the  salt  are  left  over,  while  the  100  g.  of  water  dissolve 
600  g.  of  alcohol,  but  if  more  alcohol  is  added  it  too  disap- 
pears in  the  solution. 

An  examination  of  the  phenomena  shows  that  there  is 
an  essential  difference  between  a  solid  solute  and  a  liquid 
solute  in  contact  with  a  solvent.  The  solid  solute,  except 
such  substances  as  gelatine,  does  not  absorb  or  dissolve 
the  solvent,  while  the  liquid  solute  plays  the  role  of  sol- 
vent and  the  result  is  two  solutions.  Thus,  if  dry  ether 
be  added  to  water,  the  ether  which  is  not  dissolved  does 
not  remain  anhydrous,  but  dissolves  a  considerable 
amount  of  the  water.  The  figure  600  obtained  for  the 
solubility  of  alcohol  in  water,  is  for  anhydrous  alcohol  in 
contact  with  its  solution  in  water.  If  the  alcohol  were 
separated  from  the  water  by  a  semipermeable  diaphragm, 
through  which  the  alcohol  alone  could  pass,  this  condition 
might  possibly  be  realized. 

Such  numbers  as  these,  representing  a  sort  of  ideal 
solubilities,  are  of  interest  for  the  comparison  of  the 
properties  of  the  members  of  a  series.  They  have  a  prac- 
tical value  in  the  study  of  extractions. 

The  lower  alcohols  have  been  studied  in  the  hope  of  be- 
ing able  to  arrange  them  in  a  series,  so  as  to  show  the 
variation  of  solubility  with  molecular  weight. 

It  is  difficult  to  find  a  suitable  liquid  for  the  solvent  A, 
since  most  liquids  that  are  insoluble  in  water,  dissolve  too 
much  of  the  alcohols.  Cottonseed  oil  was  chosen  on  ac- 
count of  its  insolubility  in  water,  its  non-volatility,  and 
its  accessibility.  It  served  the  purpose  only  fairly  well 


f 

Water  layer. 

Oil  layer. 

Cw/Co 

3° 

2.69 

0.09 

29.8 

3° 

3-90 

0.07 

557 

30° 

2.64 

0.14 

18.8 

30° 

3.82 

0.16 

23.8 

8 

since  it  is  rather  difficult  to  handle  and  gives  up  a  small 
amount  of  volatile  matter  when  steam  distilled.  It  mixes 
with  the  higher  alcohols,  so  only  partition  ratios  could  be 
determined  with  these. 

Meyer5  in  a  study  of  the  influence  of  temperature  upon 
the  partition  coefficient  has  determined  the  distribution 
ratio  of  ethyl  alcohol  between  olive  oil  and  water.  His 
determinations  were  made  at  3°  and  30°  with  the  follow- 
ing results : 

G.  substance  per  100  cc.  of 

Mean. 
42.7 

21.3 

The  wide  variation  in  his  results  is  due  to  the  fact  that 
he  determined  the  alcohol  in  the  oil  layer  by  difference, 
throwing  all  the  error  on  the  smaller  quantity. 

His  results  at  30°  approximate  those  obtained  in  the 
present  work  for  the  similar  cotttonseed  oil. 

MATERIALS. 

Cottonseed  OIL — The  ordinary  oil  was  purified  by  dis- 
tilling with  steam  for  about  two  hundred  hours.  When 
the  density  of  the  distillate  approached  the  density  of 
pure  water,  the  oil  was  assumed  to  be  ready  for  use.  A 
small  amount  of  alkali  in  water  was  added  to  neutralize 
and  dissolve  any  free  acid,  and  the  oil  filtered  through  a 
dry  paper  in  a  hot  water  funnel. 

Later  in  the  work  it  was  found  that  Wessen  oil  required 
only  one  day  of  distilling  with  steam  before  being  ready 
for  use,  and  it  was  then  used  in  the  place  of  the  ordinary 
commercial  oil. 

Ethyl  Alcohol. — The  ethyl  alcohol  was  refluxed  with 
lime  for  a  period  of  several  days  and  distilled.  It  had  a 
density  of  0.7854325/4  corresponding  to  99.92%  alcohol. 

Methyl  Alcohol. — Difficulty  was  experienced  in  dehy- 

5    Arch.  exp.  Path.  Pharm.,  46,  344  (1901). 


9 

drating  methyl  alcohol.  It  was  first  refluxed  with  lime 
for  several  days,  then  with  anhydrous  copper  sulf ate,  then 
finally  with  metallic  calcium.  Density  0.7958025/4  cor- 
responding to  99.95%  alcohol. 

Propyl,  Isobutyl  and  Isoamyl  Alcohols. — All  three  alco- 
hols were  refluxed  with  metallic  calcium  for  several  days 
and  assumed  to  be  practically  anhydrous.  Their  densi- 
ties were  0.8071525/4,  0.7994925/4  and  0.8122525/4,  respec- 
tively, not  corrected  for  air  displacement. 

PROCEDURE. 

Weighed  amounts  of  oil  and  water  were  placed  in  a  200 
cc.  glass  stoppered  bottle.  With  the  lower  alcohols  sev- 
eral volumes  of  oil  were  used  to  one  of  water,  so  as  to  in- 
crease the  alcohol  in  the  oil  layer.  To  this  mixture  a 
quantity  of  alcohol,  weighed  from  a  pycnometer,  was 
added.  A  piece  of  sheet  rubber  was  stretched  over  the 
stopper  and  securely  tied  around  the  neck  of  the  bottle. 
The  bottles  were  then  placed  in  the  shaking  machine  and 
shaken  for  one  hour  in  a  constant  temperature  bath  at 
25°.  The  bottles  were  completely  submerged  in  the  bath 
during  the  shaking.  It  was  found  that  it  required  three 
weeks'  standing  at  25°  for  the  layers  to  separate  clear. 
To  obviate  this  delay,  the  bottles  containing  the  mixture 
were  centrifuged  at  1350  revolutions  per  minute  until  the 
layers  became  clear.  The  temperature  of  the  centrifuge 
was  not  regulated  but  was  usually  not  far  from  25°. 

It  was  found  to  require  about  six  hours'  centrifuging 
for  the  ethyl  and  methyl  alcohol  mixtures  while  propyl, 
isobutyl  and  isoamyl  required  about  three  hours. 

The  bottles  were  then  placed  in  the  25°  bath  until  ready 
for  analysis. 

Estimation  of  Alcohol  in  Oil  Layer. — The  oil  layer  con- 
taining the  alcohol  was  drawn  off  by  means  of  a  special 
pipet,  shaped  something  like  an  Ostwald  pycnometer. 
A  suitable  amount  of  the  oil  was  weighed  out  of  the  pipet 
into  a  Kjeldahl  flask,  out  of  which  it  was  distilled  with 
steam.  The  flask  was  provided  with  an  efficient  trap  to 
prevent  splashing  over.  The  receiver  was  provided  with 


10 

a  cork  having  a  small  opening,  and  was  placed  in  an  ice 
bath  to  diminish  evaporation. 

The  alcohol  in  the  weighed  distillate  was  estimated 
either  by  the  usual  density  method  or  by  the  interfero- 
meter. For  the  interferometer  work  a  table  was  pre- 
pared for  each  alcohol.  Small  weighed  bulbs  were  filled 
with  the  anhydrous  alcohol,  sealed  and  weighed.  These 
bulbs  were  broken  in  glass  stoppered  bottles  containing 
weighed  amounts  of  water.  The  interferometer  readings 
of  a  number  of  these  mixtures  were  plotted  against  the 
percentages  of  the  alcohols.  From  this  a  table  was  cal- 
culated, which  was  used  in  determining  the  composition 
of  the  distillate. 

The  interferometer  readings  with  weighed  mixtures  of 
alcohols  and  water  are  given  in  the  following  table : 

Methyl  Alcohol. 

CH3OH%  0.821%  1,50  3.99 

Reading      0.62  1.08  2.87 

Reading  for  i% 0.75  0.72  0.72 

Propyl  Alcohol. 

C«H7OH%    1.84%  2.67  3-39  4.24 

Reading    5.75  8.57  11.07  14.48 

Reading  for   i%...3.i2  3.20  3.26  3.41 

Isobutyl  Alcohol. 

C4H9OH%    1.89%  2.95  3.18  4.21 

Reading    7.31  11.30  12.17  16.40 

Reading  for  i%..3.86  3.82  3.82  3.89 

Isoamyl  Alcohol. 

C5HWOH%    1.42%  2.31 

Reading    5.06  9.72 

Reading  for  i%  4.19  4.20 

When  cottonseed  oil  is  distilled  with  steam,  no  matter 
how  long  the  process  is  continued,  the  distillate  always 
contains  a  small  amount  of  something  which  changes  its 
density  slightly  and  also  gives  a  reading  in  the  interfero- 
meter. The  composition  of  this  distillate  remains  nearly 
constant  for  a  long  time.  The  densities  of  the  alcoholic 
distillates  were  corrected  for  this  by  taking  densities  of 


11 

distillates  obtained  with  the  same  lot  of  oil  containing  no 
alcohol.  In  the  interferometer  work  the  steam  distilla- 
tion of  the  sample  of  the  oil  layer  was  continued  for  a  con- 
siderable time  after  all  of  the  alcohol  had  passed  over. 
A  specimen  of  the  distillate  collected  at  the  end  of  this 
distillation  was  used,  instead  of  pure  water,  in  the  other 
cell  of  the  interferometer.  Since  the  interferometer  is 
a  differential  instrument,  the  reading  thus  obtained  rep- 
resented the  amount  of  alcohol  present. 

A  weighed  portion  of  the  filtered  water  layer  was  dis- 
tilled in  the  Kjeldahl  flask  and  the  alcohol  determined  as 
above. 

For  the  experiments  with  ethyl  alcohol  the  pycnometer 
was  used  and  for  the  other  alcohols  the  interferometer 
for  estimation  of  the  alcohol. 

The  absolute  solubilities  of  ethyl  and  methyl  alcohol  in 
the  oil  were  found  by  adding  a  weighed  amount  of  alcohol 
to  a  weighed  amount  of  oil  in  a  small  separating  funnel. 
The  mixture  was  then  shaken  in  a  constant  temperature 
bath  at  25°  for  two  hours. 

The  funnels  were  allowed  to  remain  in  the  bath  until 
the  layers  became  clear.  A  sample  of  the  oil  layer  was 
then  drawn  off  into  a  Kjeldahl  flask  and  steam  distilled, 
the  amount  of  alcohol  being  determined  as  in  the  above 
experiments.  The  funnel  was  weighed  before  and  after 
to  get  weight  of  sample.  Since  alcohol  evaporates  from 
this  saturated  oil  solution  very  readily,  much  care  was 
taken  to  effect  this  transfer  with  the  least  possible  ex- 
posure to  the  air,  but  even  then  it  was  difficult  to  obtain 
concordant  results. 

Weighed  portions  of  the  alcohol  layers  were  evaporated 
in  wide-mouth  weighing  bottles  on  a  steam  bath.  The 
film  of  oil  gained  weight  on  long  heating.  This  materi- 
ally interfered  with  the  accuracy  of  the  results. 

RESULTS. 

The  results  are  given  in  the  table  below. 

The  experiments  are  given  in  the  order  in  which  they 
were  made  and  none  are  omitted  except  preliminary  ex- 
periments at  beginning  of  first  two  series. 


12 


In  Column  1  is  given  volume  of  oil,  which  was  obtained 
by  dividing  the  weight  of  oil  put  in  by  0.922,  the  density 
of  the  oil  used.  In  Column  4  is  given  weight  of  alcohol 
for  the  total  oil  layer,  calculated  from  the  analysis  of  a 
weighed  portion  of  the  oil  layer,  while  in  Column  5  is  the 
amount  of  alcohol  for  the  total  water  layer  found  in  the 
same  way.  The  sums  of  these  amounts  of  alcohol  are 
given  in  Column  6.  These  sums  should  equal  the  amounts 
put  in,  which  are  given  in  Column  3.  The  amounts 
found  are  usually  less,  indicating  loss  of  alcohol  some- 
where in  the  operations.  It  is  likely  that  most  of  this 
alcohol  is  lost  in  handling  the  water  layer  as  this  had  to 
be  filtered.  Excess  of  alcohol  found  over  that  put  in  may 
be  explained  by  error  in  pycnometer  estimation  or  by 
presence  of  volatile  matter  other  than  alcohol  in  the  dis- 
tillate. The  distillates  from  the  oil  layer  were  usually 
about  60  cc.  so  that  the  total  alcohol  present  amounted 
to  only  about  2%  in  the  distillate. 

Columns  7  and  8  contain  the  amounts  of  alcohol  calcu- 
lated from  100  cc.  of  oil  and  water,  and  the  ratio  of  these 
is  given  in  Column  9,  as  the  partition  ratio  for  alcohol  be- 
tween oil  and  water. 

As  the  greatest  error  seemed  to  be  in  the  handling  of 
the  water  layer,  the  ratios  in  Column  10  were  also  calcu- 
lated, assuming  that  the  values  in  Column  4  for  alcohol 
in  oil  layers  are  correct  and  estimating  the  alcohol  in 
water  layer  by  difference,  i.  e.,  the  difference  between  the 
values  in  Columns  6  and  4.  The  values  calculated  in  this 
way  are  usually  higher  and  are  somewhat  more  regular. 

The  values  of  the  partition  ratios  have  not  been  calcu- 
lated by  difference  in  the  case  of  isobutyl  and  isoamyl 
alcohols  since  the  amounts  of  these  alcohols  in  the  two 
layers  are  more  nearly  equal,  and  the  probable  errors  of 
estimating  the  alcohols  in  the  two  layers  were  nearly  the 
same. 

Some  results  which  appear  erratic  are  in  parentheses 
and  have  not  been  used  in  making  the  averages. 


13 


I 

i 


o  +s 


• 
•  +••  O  2   O  O 

X  1-1  HH 


d  o*  d  d  o  d  o  6 


.S 


-u 


•~u 


q  q  q  q  q  S 
o  o  d  d  d  d 


Cott 


HH*O 

O    C 


Rod  vd  NO  -; 


I 


-Sri 


d  d  d  d  d  o"  d 


!^o 


*-;  O  ^00  "">  *>• 

i  >  K  2  s  «?  2 


.  10  f5  ON  O  txOO  *o 
J>      oo  ob5^  00*00  »  o? 


14 


-  •  -.a 

>  <u 


•       +J 


«.S  (j^ 
U       u 


t. 

\ 


oo 


^ 

o  *ss*o 


ooooooooooooo 


ffi 


U  C 


t-H      .   Tf 


OO  1000   i-"   rO  OsVO  OO 


ddddddddddddd 


ioOvD  (M  O  txOO  t*x  ro 
O<lN.ON  1OOO  10  CO  C^OO 
•MQ   O\O   CO^   HH  VOHH   rotxtxM   O\io 

>  S  *>  ^  ^QQ  <^  q  <N  oq  looq  M  \5  oq 
?>  ffi  ci  ro  oi  oi  ci  ro  co  <N  o<  oi  co  oi  oi 
U 


>°R< 


ON  CO  Q*   •-* 
txOO  OO  OO 


15 


*    +1 

!*• 

U 


£     o 

w   > 
.S       ' 


.ts  vd  "•>  vd  vd  vd  vd 


o  M  6 


*EON~  01 
tr  io\o  co 
G  01  ooo 


CO 


i 

w 

o 
>, 


-•Bo 


O    ^§«1Hllfl|  5 


ffi  Q 

3§ 


! 

Qu 


OO   0\00 


*S.a 


.K 
3 


.    01    01    10  10  O    M 

n:  f?  o  Tt-  q  M  01 

O   OJ   ro  ^O  ro  i-O  ro 
GO  00  OOOO  OOOO 


16 


•SO 


3| 


•ffi  ° 

SQ8 

E  8 
U§ 


c^S 


O   04'   CO  04   04 


w  o 


HH      « 


I  *m 


73         — : 

O  ^jffi 

•J  £^83 

!      E8 

g      u~ 

o        ffi    , 

U  ^g-HS- 


CO         V 
1O  ID 

H-i    O 

ON  IH 


u  H*  o  6  M  o  o 


K 

as 


tX   O\  t^  IO 


& 


1 


!       K  c 
o       J- 


to 

«  H  o'  ON  C  8 


i§ 

"ffi 

U 


CO  CO  OJ   04*   04*   CO 


I  £ 


K 


Tj   to  txOO   ON  04  *O 

*"^  \O   COOO   *™^   co  O 

—- '     TJ-   OJ     HH     Tf-   IO  tX 
O    tX  tX   tX  tX  tX  tX 


..ioqoq 
£>a?oooo  oo  o?oo 


K>  00  00  00  00  00  00 


DISCUSSION  OF  RESULTS. 


The  average  results  are  brought  together  in  table,     j 

Partition  Ratio  Between  Water  and  Cottonseed  Oil.  ] 


Alcohol.  Methyl. 

Ratio    103.6 

Square  root  of  ratio  ..  10.18 


•0 


^  9 

5    6 

I7 

$    6 


Ethyl.  Propyl.    Isobutyl.  IsoamyL 
28.3  6.41  1.70  047 

5.32         2.53  1.30          0.68 


t 


5' 


012345 
Number  of  Carbon  Atoms 
in  AJcoho/s. 

17 


18 

The  ratios  decrease  rapidly  as  the  number  of  carbon 
atoms  in  the  alcohol  increase,  each  ratio  being  approxi- 
mately one-fourth  of  the  preceding  ratio. 

Taking  these  ratios  as  fractions,  the  numerators  which 
represent  the  solubilities  of  the  alcohols  in  water,  in- 
crease as  number  of  carbon  atoms  decrease,  while  the  de- 
nominators, or  the  solubilities  of  the  alcohols  in  the  oil 
increase  in  the  opposite  directions.  For  this  reason  the 
square  roots  of  these  ratios  have  been  plotted  against 
number  of  carbon  atoms  in  the  curve.  (See  page  17). 

The  solubility  of  methyl  alcohol  in  cottonsed  oil  appears 
to  be  4.84  g.  per  100  cc.  while  for  ethyl  alcohol  it  is  21.2 
or  about  four  times  as  great.  We  have  4.84  x  103.6  = 
505  and  21.2  X  28.3  =  600.  From  this  505  g.  methyl 
alcohol  and  600  g.  ethyl  alcohol  should  dissolve  in  100  cc. 
water.  These  represent,  in  the  same  approximation, 
what  may  be  termed  ideal  solubilities.  At  any  rate  the 
numbers  4.84  and  103.6  represent  something  real  as  de- 
termined by  experiment  and  their  product  must  have 
some  meaning  also.  Further  work  will  have  to  be  done 
before  these  results  can  be  satisfactorily  interpreted.  It 
is  surprising  that  methyl  alcohol  gives  the  smaller  num- 
ber 505,  while  ethyl  alcohol  gives  the  larger  number  600. 
It  was  expected  that  methyl  alcohol  would  give  the  larger 
number  as  the  fact  that  methyl  alcohol  is  more  difficult  to 
salt  out  of  a  solution  than  ethyl,  seems  to  indicate  a  greater 
affinity  for  water  and  hence  a  greater  solubility  in  water. 
The  difficulty  may  be  in  the  numbers  4.84  and  21.2,  the 
directly  determined  solubilities  of  the  two  alcohols  in  the 
oil.  These  do  not  represent  the  amounts  of  alcohol  taken 
up  by  the  oil  when  in  contact  with  the  pure  alcohols,  but 
the  amounts  in  the  oil  when  the  oil  is  in  contact  with  solu- 
tions of  the  oil  in  the  two  alcohols.  If  we  consider  mole- 
cular solubilities,  the  order  is  what  we  should  expect, 
since  505  -f-  32  =  15.8  and  600  -4-  46  =  13.0.  Taking 
the  higher  and  more  concordant  values  we  find  that  100  g. 
of  methyl  alcohol  dissolve  8.45  g.  of  cottonseed  oil  and 
100  g.  ethyl  alcohol,  11.75  g. 

Experiments  showed  that  propyl,  isobutyl,  and  isoamyl 


19 

alcohols  mix  with  cottonseed  oil  in  all  proportions.  This 
prevented  the  determinations  of  their  direct  solubilities. 
The  solubilities  of  isobutyl  and  isoamyl  alcohols  in  100  cc. 
water  are  given  in  the  tables  as  9.55180  and  2.67220.  Ac- 
cording to  the  above  reasoning,  the  solubilities  of  these 
two  alcohols  in  the  oil  should  be  9.55  -H  1.70  =  5.6  and 
2.67  -H  0.47  =  5.6.  This  shows  that  we  must  be  guarded 
in  drawing  conclusions  and  that  there  are  factors  which 
are  not  taken  into  consideration  in  the  reasoning  as  stated 
above. 

These  alcohols,  when  they  contain  a  few  per  cent,  of 
water,  do  not  mix  with  the  oil.  The  phenomena  of  mu- 
tual solubility  are  quite  complex  and  require  much  fur- 
ther study.  This  work  is  being  continued  in  this  labora- 
tory. 


SUMMARY. 

1.  The  partition  ratios  of  methyl,  ethyl,  propyl,  iso- 
butyl  and  isoamyl  alcohols  between  water  and  cottonseed 
oil  at  25°  are  found  to  be  103.6,  28.3,  6.41,  1.70  and  0.47, 
respectively. 

2.  These  are  found  to  change  regularly  with  increased 
number  of  carbon  atoms. 

3.  The  solubilities  of  methyl  and  ethyl  alcohols  in 
cottonseed  oil  are  4.84  and  21.2  g.  per  100  cc.  oil. 

4.  The  attempt  has  been  made  by  using  these  num- 
bers and  the  partition  law  to  calculate  the  ideal  solubili- 
ties of  the  lower  alcohols  in  water. 


20 


BIOGRAPHY. 

Benjamin  Blackiston  Wroth  was  born  November  10, 
1887,  in  Chestertown,  Maryland.  He  received  his  early 
education  in  the  public  schools  of  Chestertown.  In  the 
autumn  of  1904  he  entered  Washington  College,  Mary- 
land, from  which  he  graduated  in  1908  receiving  the  de- 
gree of  Bachelor  of  Arts.  After  graduation  he  taught 
for  four  years  in  the  grammar  and  high  schools  of  this 
State.  In  1912  he  entered  Johns  Hopkins  University  as 
a  graduate  student  in  Chemistry.  His  subordinate  sub- 
jects were  Physical  Chemistry  and  Physics. 


21 


UNIVERSITY  OF  CALIFORNIA   LIBRARY 
BERKELEY 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 

Books  not  returned  on  time  are  subject  to  a  fine  of 
50c  per  volume  after  the  third  day  overdue,  increasing 
to  $1.00  per  volume  after  the  sixth  day.  Books  not  in 
demand  may  be  renewed  if  application  is  made  before 
expiration  of  loan  period. 


PAT.  JAN.  21 ,1908 


371462          > 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


